Cross-linked chromatin was sonicated with a Covaris ME220 ultrasonicator 1-2 mg of cross-linked extract was immunoprecipitated, and prepared for illumina library construction by repair with Klenow, T4 DNA polymerase and T4 polynucleotide kinase, A-tailing with Klenow exo-, ligation to branched adaptors, SPRI bead purification of ~200bp fragments, and amplification (15-18 cycles) with Illumina Tru-seq primers using Phusion DNA polymerase.